1. Field of the Invention
The present invention relates to the preparation of aluminum phosphate-alumina compositions useful as catalyst supports and catalysts comprising the aluminum phosphate-alumina compositions.
2. Description of the Prior Art
It is known to prepare aluminum phosphate-alumina compositions by various methods. Catalysts comprising aluminum phosphate-alumina s a catalyst support or catalyst component are known.
U.S. Pat. No. 3,904,550 discloses a process for the preparation of an aluminum phosphate-alumina which comprises reacting an aluminum alkoxide with an aqueous solution of a phosphorus-containing acid such as phosphoric acid or a soluble salt thereof.
U.S. Pat. Nos. 3,271,299 and 3,342,750 disclose a process for the preparation of alumina-aluminum phosphate gels by reaction of aluminum chloride, phosphoric acid and ethylene oxide.
U.S. Pat. No. 4,080,311 discloses a process for the preparation of thermally stable alumina-aluminum phosphate precipitates having a surface area in the range of 100 to 200 m.sup.2 /g by mixing an inorganic aluminum salt and phosphoric acid. The mixture is neutralized with ammonia or an ammonium sol to produce the precipitate.
U.S. Pat. No. 4,066,572 discloses a method for the production of a phospha-alumina gel in which an inorganic aluminum salt is mixed with an inorganic phosphorus salt followed by the adjustment of the pH to precipitate the gel.
U.S. Pat. No. 3,879,310 discloses an alumina having a uniformly distributed PO.sub.4 content from about 1% to about 20% by weight and a surface area of at least 300 m.sup.2 /g after heating the composite to 600.degree. C. for 2 hours.
Although high surface area aluminum phosphate-alumina has been prepared by the ethylene or propylene oxide plus aluminum chloride process, the products are difficult to extrude, and the process requires refrigeration. Preparation of aluminum phosphate-alumina by the prior art phosphoric acid-water hydrolysis of aluminum alkoxide yield products of lower surface areas. Attempts to incorporate metals such as molybdenum or tungsten into the alumina-aluminum phosphate prepared by the phosphoric acid procedure usually resulted in a considerable reduction of the surface area of the resulting products.
It has now been found that high surface area aluminum phosphate-alumina can be produced which, when composited with metal components, will have a minimal decrease in surface area.